PARETO OPTIMAL OPERATING SOLUTIONS FOR A CATALYTIC REACTOR FOR BENZENE OXIDATION BASED ON SAFETY INDICES AND AN EXTENDED PROCESS KINETIC MODEL

摘要

The importance of process safety in every life cycle stage of a (petrochemical plant is in continuous growth nowadays. The ability of handling highly exothermic reactions conducted in the presence of parametric uncertainty is related to rules and algorithms to find optimal operating policies of the chemical reactor by simultaneously considering several objectives of sustainability: the contrary process optimization objectives involve, besides economic aspects (process yield, reactor productivity), safety characteristics, such as controllability, stability, and runaway risk. During reactor optimization, the safety aspects must always prevail, without disregarding economic aspects. This paper exemplifies an original methodology to generate the Pareto optimal operating policies of a hazardous chemical reactor, when reactor productivity and safety objectives (expressed in probabilistic terms) are simultaneously considered by using the process and reactor model in a simple way, in the presence of technological constraints, uncertainty in safety boundaries, and random fluctuations in control variables. An example is provided for an industrial fixed-bed tubular reactor, of high thermal sensitivity, used for the catalytic oxidation of benzene to maleic anhydride in vapour phase. Extended process kinetics allows a more accurate determination of the acceptable trade-off between reactor productivity and its safe operation.